NVRR 73 is one of four ex-CN FPA4 engines used on the Napa Valley Wine Train. These vintage engines were originally built for the Canadian National Railways and were used for passenger service for many years before being retired.
NVRR 73 was converted to burn compressed natural gas. It has an EMD 12-645E engine instead of the original Alco engine.
The FPA4 engines contained steam generators to provide heat for the passenger cars. On the Napa Valley Wine Train, the generators have been replaced by generators to provide Head End Power (HEP) to supply electricity to the attached train.